Predicting the unpredictable; evidence of pre-seismic anticipatory behaviour in the common toad

The widespread belief that animals can anticipate earthquakes (EQs) is poorly supported by evidence, most of which consists of anecdotal post hoc recollections and relates to a very short period immediately before such events. In this study, a population of reproductively active common toads Bufo bufo were monitored over a period of 29 days, before, during and after the EQ (on day 10) at L'Aquila, Italy, in April 2009. Although our study site is 74 km from L'Aquila, toads showed a dramatic change in behaviour 5 days before the EQ, abandoning spawning and not resuming normal behaviour until some days after the event. It is unclear what environmental stimuli the toads were responding to so far in advance of the EQ, but reduced toad activity coincides with pre-seismic perturbations in the ionosphere, detected by very low frequency (VLF) radio sounding. We compare the response of toads to the EQ with the reported responses to seismic activity of several other species.